1. The Inscription. Who was Isaiah? Of what sort was his death?
Among the נביאים אחרונים, latter Prophets, even indeed the גדלים, the Major Prophets, ישעיה/Isaiah, that is, the salvation of the Lord, or חֲזוֹן֙ יְשַֽׁעְיָ֣הוּ, the vision of Isaiah, or the Prophecy of Isaiah, obtains the first place. He was the בֶן־אָמוֹץ, son of Amoz, who was not indeed that Amos, the Prophet of Tekoa, but, if confidence is to be granted to the ancient Rabbis, was the brother of King Amaziah, although the authority of the ancient Rabbis be not such, that we dare to affirm it as certain, especially since their conjectures to pass into tradition. Neither is it sufficiently evident when, or with what sort of death he was removed. For what the Talmudists asserts, and appears to be insinuated by some Christian interpreters, ancient and more recent, on Hebrews 11:37, namely, that he was sawn asunder by Manasseh, also rests upon an uncertain tradition, and is not deserving of strong confidence, or on this account, that Isaiah is not said to have prophesied under Manasseh, Isaiah 1:1, where those under whom he prophesied are related. In Ecclesiasticus 48:22, he is called ὁ προφήτης ὁ μέγας καὶ πιστὸς, the Prophet great an faithful. He is to be called, no so much a Prophet, as an Evangelist, as Saint Jerome knowledgeably judges, Præfatione in Esajæ. He adds, For he describes the whole mystery of Christ and the Church in such detail that you might think that he is not prophesying of the future, but composing a history of past things.
יָשַׁע signifies to save; יָה/Yah is an abbreviation of the Divine Name.  Isaiah 1:1.  Ecclesiasticus 48:20-25: “But they called upon the Lord which is merciful, and stretched out their hands toward him: and immediately the Holy One heard them out of heaven, and delivered them by the ministry of Esay. He smote the host of the Assyrians, and his angel destroyed them. For Ezekias had done the thing that pleased the Lord, and was strong in the ways of David his father, as Esay the prophet, who was great and faithful in his vision, had commanded him. In his time the sun went backward, and he lengthened the king’s life. He saw by an excellent spirit what should come to pass at the last, and he comforted them that mourned in Sion. He shewed what should come to pass for ever, and secret things or ever they came.”